Multi-capillary electrophoresis apparatus

ABSTRACT

Errors upon analysis caused by, fluctuation in electrophoresis time among plural capillaries in a multi-capillary electrophoresis apparatus is reduced. The multi-capillary electrophoresis apparatus contains a multi-capillary array that has an isolation medium filled therein for isolating a sample, has a sample injecting end on one end thereof, and has, at a position remote from the sample injecting end, a detector part for acquiring information depending on the sample, a voltage applying part for applying a voltage to an electrification path containing the sample injecting end and the detector part, a thermostat oven containing all or a part of the multi-capillary array except for the sample injecting end, a buffer container containing a buffer solution, in which the sample injecting end is immersed, and a temperature controlling part for controlling a temperature of the buffer solution.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a multi-capillaryelectrophoresis apparatus having a multi-capillary array formed withplural capillaries each having a sample and an isolation medium filledtherein, and more particularly, to an apparatus that can suppressmeasurement fluctuation upon analysis with a multi-capillaryelectrophoresis apparatus.

[0002] In recent years, a capillary electrophoresis apparatus having acapillary having an electrophoretic medium (isolation medium) filledtherein, such as a high-polymer gel and a polymer solution, has beendeveloped as shown in Japanese Laid-open Patent Publication JP-A6-138037. A capillary electrophoresis apparatus has high heatdissipation capacity and can be applied with a high voltage, incomparison to the conventional slab gel electrophoresis apparatus, andtherefore, it has such an advantage that electrophoresis can be carriedout at a high rate.

[0003]FIG. 11 shows a schematic structure of an ordinary capillaryelectrophoresis apparatus. As shown in FIG. 11, the capillaryelectrophoresis apparatus B has a capillary part 103, a thermostat oven105, a detector part 107 and a buffer container 111.

[0004] The capillary part 103 is formed with plural capillaries 103 a.The buffer container 111 is filled with a buffer solution 111 a. Asample and an isolation medium for isolating the sample are filled inthe capillary 103 a. One end 103 b of the capillary 103 a is immersed inthe buffer solution 111 a. The other end 103 c of the capillary 103 a isalso immersed in, for example, a buffer solution.

[0005] The detector part 107 is retained with a retaining part 107 b forretaining the capillaries 103 a. The detector part 107 is housed in theretaining part 107 b and a cover member 108. A high voltage is appliedbetween the end 103 b and the other end 103 c of the capillary 103 a,whereby the sample is electrophoresed in the isolation medium. Thesample thus isolated by electrophoresis is detected in the detector part107 with an optical means. The retaining part 107 b has a window part107 c for taking out fluorescence excited by the optical means.

[0006] In the capillary electrophoresis apparatus, Joule heat isgenerated upon applying a high voltage between the both ends 103 b and103 c of the capillary 103 a. In particular, air dissolved in the liquidof the isolation medium forms bubbles upon local increase of thetemperature to rise the resistance of the isolation medium. When theisolation medium has high resistance, the electrophoresis migrationvelocity is lowered to cause adverse affects, such as deterioration inresolution power of the sample. In general, in order to prevent localgeneration of heat in the capillaries 103 a, it has been widely operatedthat the capillaries 103 a are placed in the thermostat oven 105,whereby the electrophoresis is carried out under the conditions wherethe temperature is maintained constant.

[0007] However, it is actually difficult to place the entire length ofthe capillaries in the thermostat oven. For example, the end 103 bforming a sample injecting end for injecting the sample and the detectorpart 107 for detecting the sample with an optical means are not placedin the thermostat oven 105.

[0008] The sample injecting end 103 b is difficult to be placed in thethermostat oven because maintenance is necessary for injecting thesample from the sample injecting end 103 b. Furthermore, the ends 103 band 103 c of the capillary 103 a are immersed in the buffer solution 111a for electrophoresis. Therefore, it has been difficult to place theends 103 b and 103 c and the vicinity of the detector part 107 in thethermostat oven 105 that contains the central part of the capillaries(electrophoresis part).

[0009] In a multi-capillary apparatus having plural capillaries, thetemperature of the isolation medium in the radial direction of thecapillaries are liable to be fluctuated among the plural capillaries. Inparticular, it is often the case that the temperature is differentbetween the capillaries arranged in the periphery and the capillariesarranged in the central part. It is considered that this is because thecapillaries arranged in the periphery are liable to be affected by theoutside air.

[0010] The temperature of the isolation medium in the capillaries at thesample injecting end 103 b and a detecting part 103 d is liable to bedifferentiated from the temperature thereof inside the thermostat oven105, and therefore, there is a possibility that the electrophoresis timeis fluctuated.

[0011] A light emission part emitting, for example, laser light to thedetector part 107 is provided, and a CCD image sensor (or a CCD camerahaving the same) is also provided for receiving the laser light incidenton the detecting part 103 d. Thermal noise of the CCD image sensor isincreased by the influence of heat.

[0012] In order to reduce the thermal noise, it is necessary that theCCD image sensor arranged in the vicinity of the detector part 107 ismaintained at a low temperature as much as possible. Accordingly, it isnot preferred that both the detector part 107 and the CCD image sensorare placed in the thermostat oven 105.

[0013] Therefore, in the detector part 107, the temperature of theisolation medium in the radial direction of the capillaries is liable tobe fluctuated among the plural capillaries.

[0014] The temperature of the isolation medium in the electrophoresispart that is maintained constant with the thermostat oven 105 is sharplydecreased in the vicinity of the detector part 107. When there istemperature fluctuation in the longitudinal direction of thecapillaries, there is a possibility that the electrophoresis time isfluctuated.

SUMMARY OF THE INVENTION

[0015] An object of the invention is to provide a multi-capillaryelectrophoresis apparatus having a multi-capillary array containingplural capillaries in that fluctuation of the temperature, particularlyfluctuation of the temperature in the radial direction, is reduced,whereby errors upon analysis caused by, for example, fluctuation of theelectrophoresis time are reduced.

[0016] The invention relates to, as one aspect, a multi-capillaryelectrophoresis apparatus containing a multi-capillary array that has anisolation medium filled therein for isolating a sample, a sampleinjecting end on one end thereof, and a detector part for acquiringinformation depending on the sample at a position remote from the sampleinjecting end, a voltage applying part for applying a voltage to anelectrification path containing the sample injecting end and thedetector part, a thermostat oven containing all or a part of themulti-capillary array except for the sample injecting end, a buffercontainer containing a buffer solution, in which the sample injectingend is immersed, and a temperature controlling part for controlling atemperature of the buffer solution.

[0017] The invention also relates to, as another aspect, amulti-capillary electrophoresis apparatus containing a multi-capillaryarray that has an isolation medium filled therein for isolating asample, a sample injecting end on one end thereof, and a detector partfor acquiring information depending on the sample at a position remotefrom the sample injecting end, a voltage applying part for applying avoltage to an electrification path containing the sample injecting endand the detector part, a thermostat oven containing all or a part of themulti-capillary array except for the detector part, and a temperaturecontrolling part for controlling a temperature of the detector part.

[0018] The invention also relates to, still another aspect, amulti-capillary electrophoresis apparatus containing a multi-capillaryarray that has an isolation medium filled therein for isolating asample, a sample injecting end on one end thereof, and a detector partfor acquiring information depending on the sample at a position remotefrom the sample injecting end, a voltage applying part for applying avoltage to an electrification path containing the sample injecting endand the detector part, a thermostat oven containing all or a part of themulti-capillary array except for the sample injecting end and thedetector part, a buffer container containing a buffer solution, in whichthe sample injecting end is immersed, a temperature controlling part forcontrolling a temperature of the buffer solution, and a temperaturecontrolling part for controlling a temperature of the detector part.

[0019] The temperature of the capillaries is controlled by thetemperature controlling part, whereby fluctuation of the electrophoresistime in the radial direction among the plural capillaries isparticularly reduced, and thus accurate analysis can be carried out forplural samples.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a diagram showing the overall structure of themulti-capillary electrophoresis apparatus according to one embodiment ofthe invention, and FIG. 1 also shows the structure of the temperaturecontrolling part (E).

[0021]FIGS. 2A and 2B are diagrams showing the structure of theelectrode in the multi-capillary electrophoresis apparatus according toone embodiment of the invention, and FIG. 2C is a diagram showing thestructure of the capillary in the vicinity of the sample injecting endinserted in the electrode.

[0022]FIGS. 3A and 3B are diagrams showing the structures of the buffercontainer (A) and the temperature controlling part (A) installed thereinfor controlling the temperature of the buffer solution (A) in themulti-capillary electrophoresis apparatus according to one embodiment ofthe invention.

[0023]FIGS. 4A to 4C are diagrams showing the structure of the detectorpart in the multi-capillary electrophoresis apparatus according to oneembodiment of the invention.

[0024]FIGS. 5A to 5C are diagrams showing the structures of thecontainer part containing the detector part and the temperaturecontrolling part (B) controlling the temperature of the detector part inthe multi-capillary electrophoresis apparatus according to oneembodiment of the invention, and also showing the arrangement of theoptical means.

[0025]FIGS. 6A and 6B are diagrams showing the structure of thetemperature controlling part (C) controlling the temperatures among thecapillaries in the vicinity of the outlet of the thermostat oven in themulti-capillary electrophoresis apparatus according to one embodiment ofthe invention.

[0026]FIG. 7A is a diagram showing the structures of the gel block, thebuffer container (B) having the buffer solution (B) filled therein, andthe conduit connecting them in the multi-capillary electrophoresisapparatus according to one embodiment of the invention, and particularlyshowing the structure of the temperature controlling part (D)controlling the temperature of the conduit and the buffer container (B).FIG. 7B is a side view of the cover member of the buffer container (B).

[0027]FIG. 8 is a diagram showing the relationship between thecontrolling part and the respective temperature controlling parts in themulti-capillary electrophoresis apparatus according to one embodiment ofthe invention.

[0028]FIG. 9 is a graph showing a standard deviation of theelectrophoresis time among the capillaries upon using themulti-capillary electrophoresis apparatus according to one embodiment ofthe invention.

[0029]FIG. 10 is a diagram showing the structure of the detector part inthe multi-capillary electrophoresis apparatus according to a modifiedembodiment of the invention.

[0030]FIG. 11 is a diagram showing the schematic structure of anordinary multi-capillary electrophoresis apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] As a result of earnest experimentation and investigations made bythe inventors with respect to a multi-capillary electrophoresisapparatus, it has been found that fluctuation in analytical result amongthe capillaries of the multi-capillary array having plural capillariescan be suppressed by controlling the temperature of the buffer solution,in which the sample injecting end is immersed, with, for example, aheater.

[0032] Furthermore, it has been also found that fluctuation inanalytical result among the plural capillaries can be suppressed bycontrolling the temperature of the detector part, particularly thetemperature in the vicinity of the detecting part of the capillaries tobe inspected.

[0033] A multi-capillary electrophoresis apparatus according to oneembodiment of the invention will be described with reference to FIG. 1to FIG. 9.

[0034]FIG. 1 is a diagram showing the overall structure of themulti-capillary electrophoresis apparatus according to one embodiment ofthe invention.

[0035] As shown in FIG. 1, the multi-capillary electrophoresis apparatusA according to one embodiment of the invention has a multi-capillaryarray 3 containing plural capillaries 3 a installed in a container partCS in a thermostat oven 5. The multi-capillary array 3 has plural, forexample, 16 capillaries 3 a.

[0036] A sample 4 a containing, for example, specimens of DNA molecules,and an isolation medium 4 b functioning as a medium for isolating theDNA molecules in the sample 4 a has been filled in the capillaries 3 a.The isolation medium 4 b is constituted with, for example, a polymer ina gel form (FIG. 2C).

[0037] The DNA fragment sample contained in the sample 4 a can bedistinguished by labeling the primer or the terminator with afluorescent substance using the Sangar dideoxy method. The DNA fragmentsample thus labeled with a fluorescent substance can be distinguished bythe optical means described later.

[0038] One end of the capillary 3 a constitutes an injecting end 3 b forinjecting the sample 4 a by protruding from the bottom of the thermostatoven 5. The injecting end 3 b is immersed in a buffer solution (A) 11 a.The buffer solution (A) 11 a is contained in a buffer container (A) 11.A electrode (A) 6 a is mounted on the introducing part 3 b.

[0039] The other end of the capillary 3 a protrudes from the side of thethermostat oven 5, and through a detector part 1 for acquiringinformation depending on the sample 4 a, forms an end part 3 d of thecapillaries by packing the plural capillaries 3 a at a capillary fixingpart 35. The end part 3 d is connected to an upper gel block 34. Theupper gel block 34 is connected to a buffer container (B) 15 having abuffer solution (B) 15 a filled therein, a gel storage container 25having a gel (isolation medium) 34 c filled therein, and a syringe 31.

[0040] As shown with the broken line, a thermostat oven RH may beprovided to contain at least one of the upper gel block 34, the buffercontainer 15 and the syringe 31.

[0041] The multi-capillary electrophoresis apparatus A according to theembodiment has at least one temperature controlling part among first totemperature controlling part (E)s TCM1 to TCM5, in addition to atemperature controlling part TCM0, which has been provided in anordinary multi-capillary electrophoresis apparatus, for controlling thetemperature of the capillaries 3 a with the thermostat oven 5.

[0042] The multi-capillary electrophoresis apparatus according to theembodiment will be described in detail below with a focus on thetemperature controlling parts.

[0043] The temperature controlling part (A) will be described withreference to FIGS. 1 to 3B. The end of the sample injecting end 3 b ofthe capillary 3 a is immersed in the buffer solution (A) 11 a. Thebuffer solution (A) 11 a is filled in the buffer container (A) 11. Asshown in FIG. 2A, a electrode (A) 6 a as an electrode on the side of thesample injecting end 3 b is formed by pressing stainless-steel tubes 6a-1 made of stainless steel into a metallic plate 6 a-2.

[0044] As shown in FIG. 2B, the sample injecting end 3 b is inserted inthe stainless-steel tubes 6 a-1 to integrate the sample injecting end 3b and the electrode (A) 6 a. A positive electrode of a direct currentpower supply 21 (FIG. 1) is connected to the electrode (A) 6 a throughan electrode (not shown in the figure) of the apparatus. Under theconditions where the sample injecting end 3 b is inserted in thestainless-steel tubes 6 a-1, the electrode (A) 6 a is installed in acover PC made with a resin. As shown in FIG. 2C, the isolation medium 4b is filled in the capillaries 3 a, and the sample 4 a is filled in thevicinity of the sample injecting end 3 b.

[0045] As shown in FIG. 1 and FIG. 3A, the sample injecting end 3 b andthe electrode (A) 6 a are immersed in the buffer solution (A) 11 afilled in the buffer container (A) 11. The buffer solution (A) 11 a isprepared with, for example, TBE (a mixed solution of tris(hydroxymethyl) aminomethane, boric acid and EDTA(ethylenediaminetetraacetic acid)) or TAPS(N-tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid).

[0046] The buffer container (A) 11 is installed in an adapter AD havingan opening on an upper part thereof. The adapter AD has a rubber heater12 laid on the inner bottom surface thereof.

[0047] The rubber heater 12 and the adapter AD are waterproofed bysealing with silicone rubber SG. An opening 12 c is formed on an outerbottom surface 12 b′ of the adapter AD. A thermistor (temperaturemonitor) TM is attached to the back surface of the rubber heater 12 bexposed from the opening 12 c, and a first cable CB1 connected to thethermistor TM. Furthermore, a second cable CB2 connected to a powersupply PS for the heater and a fuse FS is attached to the back surfaceof the rubber heater 12 b.

[0048] The temperature within the surface of the buffer container (A) 11in contact with the rubber heater 12 b can be made constant by using therubber heater 12 b. Maintenance operations, such as replacement of theheater, can be conveniently carried out by using such a structure thatthe buffer container (A) 11 is placed on the adapter AD lined with therubber heater 12 b.

[0049] While the rubber heater 12 b is arranged in contact with thebuffer container (A) 11, the term “contact” herein is not limited tosuch a constitution that both the members are physically and directly incontact with each other, but both the members may be, for example, inindirectly contact with each other. In other words, a sheet having ahigh heat conductance may be inserted between both the members. Inessence, the term means that both the members are thermodynamicallyconnected.

[0050] The temperature difference of the isolation medium 4 b in theplural sample injecting ends 3 b can be suppressed by using thetemperature controlling part (A) TCM1.

[0051] The temperature controlling part (B) TCM2 controlling thetemperature of the detector part 1 will be described with reference toFIGS. 4A to 5C.

[0052] As shown in FIGS. 4A to 4C, the multi-capillary 3 formed withplural capillaries 3 a is supported by clipping between a capillarysupporting part 77 made with, for example, a glass plate, and a pressingmember 78. An outer periphery of the capillaries 3 a is covered with alight shielding resin 51 a, such as polyimide. A region that is notcoated with the light shielding resin 51 a is provided on the outerperiphery of the capillaries 3 a between the capillary supporting part77 and the pressing member 78.

[0053] The region is irradiated with laser light L. The region isreferred to as a detecting part 3 c. An opening 78 a is formed in theregion containing the detecting part 3 c in the pressing member 78.Excitation light K generated upon irradiating the sample with the laserlight is radiated to the exterior through the opening 78 a. Thestructures described herein are totally referred to as a detector part.

[0054] Fluctuation in intensity depending on the position of the laserlight L incident on the capillaries 3 a can be suppressed by irradiatingthe capillaries 3 a with the laser light L from both above and beneath.

[0055] As shown in FIGS. 5A to 5C, the capillary supporting part 77 andthe pressing member 78, as well as the multi-capillary 3 supportedtherebetween, are contained in a container part 7. The container part 7is constituted with a main body 7 a and a cover member 7 b. The mainbody 7 a and the cover member 7 b are rotatablly connected with a hingeHG as a central axis.

[0056] The main body 7 a has a container part (A) 7 a-3, which cancontain the capillary supporting part 77 and the pressing member 78, agroove (A) 7 a-1 and a groove (B) 7 a-2, which are connected to thecontainer part (A) 7 a-3 and extend toward both sides, and a protrusionpart 7 a-4, which is connected to the groove (B) 7 a-2 and protrudesfrom the side surface of the main body. The groove (A) 7 a-1, the groove(B) 7 a-2 and the protrusion (A) part 7 a-4 have a flat plane, on whichthe multi-capillary 3 can be arranged. The container part (A) 7 a-3forms a concave part that is deeper than the flat plane. An opening 7a-5 penetrating the main body 7 a is formed in the concave part.

[0057] In the cover member 7 b, on the other hand, a spring member SP isprovided at a position corresponding to the container part (A) 7 a-3.Upon closing the cover member 7 b, the spring member SP presses thecapillary supporting part 77, whereby the multi-capillary array 3 isstrongly supported. A convex part (A) 7 b-1 and a convex part (B) 7 b-2engaging with the groove (A) 7 a-1 and the groove (B) 7 a-2,respectively, are provided at positions corresponding to the grooves onboth sides of the spring member SP. A protrusion (B) part 7 b-3extending from the convex part (B) 7 b-2 is also provided at a positioncorresponding to the protrusion (A) part 7 a-4.

[0058] In the case where the cover member 7 b is closed, the protrusionpart formed with the protrusion (A) part 7 a-4 and the protrusion (B)part 7 b-3 is contained in a concave part 35′ formed in the upper gelblock 34 (FIG. 1) to connect the container part 7 and the upper gelblock 34.

[0059]FIG. 5B shows such a state that the capillary supporting part 77and the pressing member 78 are contained in the container part (A) 7a-3, and the multi-capillary array 3 is contained in the container part(A) 7 a-3, the groove (A) 7 a-1 and the groove (B) 7 a-2. Laser devices61 emitting laser light are provided above and beneath the main body 7a. A through hole (A) 7 c-1 and a through hole (B) 7 c-2 are formed,whereby laser light L reaches a position corresponding to the detectingpart 3 c (FIG. 4B).

[0060] Upon emitting the laser light L from the laser devices 61, thesample 4 a in the detecting part 3 c is irradiated with the laser lightL to generate excitation light K. The excitation light K is emitted fromthe opening 7 a-5 and detected with a photo-accepting unit, such as aCCD camera 71 having a CCD image sensor 73.

[0061] The temperature controlling part (B) TCM2 provided in thevicinity of the detector part 1 contains, for example, at least one of arubber heater (A) 8 b-1 and a rubber heater (B) 8 b-2, which areattached to the surfaces of the groove (A) 7 a-1 and the groove (B) 7a-2 facing the cover part 7 b, respectively, and a rubber heater (C) 8a-1 and a rubber heater (D) 8 a-2, which are attached to the surfaces ofthe protrusion (A) part 7 b-1 and the protrusion (B) part 7 b-2 facingthe main body 7 a, respectively. Furthermore, a temperature monitor 8 cis provided in the vicinity of the container part (A) 7 a-3. A thermalconductor sheet may be attached instead of the rubber heaters, or inalternative, a rubber heater and a thermal conductor sheet may beaccumulated and attached.

[0062] Upon closing the cover part 7 b, the cover part 7 b and the mainbody 7 a may be fixed with a fixing screw FS. The term “vicinity” of thedetector part 1 herein means a region where the temperature of thedetector part 1 can be directly or indirectly controlled. For example,the heater may be provided on an outer peripheral surface of thecontainer part 7.

[0063] The temperature difference of the isolation medium among thecapillaries of the multi-capillary array at the detector part 1 can besuppressed by the temperature controlling part (B) TCM2.

[0064] The temperature controlling part (C) TCM3 will be described withreference to FIGS. 6A and 6B. The multi-capillary 3 in the capillarycontaining part CS in the thermostat oven 5 is connected to the detectorpart 1 through the thermostat oven 5. An opening is formed on a side(outlet) of the detector part 1 in the thermostat oven 5. A concave part5 a-1 is formed on a main body 5 a of the thermostat oven 5, and aconvex part 5 b-1 engaging with the concave part 5 a-1 is formed on acover part 5 b of the thermostat oven 5. The multi-capillary array 3 isinserted in a gap formed between the concave part 5 a-1 and the convexpart 5 b-1 formed upon closing the cover part 5 b.

[0065] The temperature controlling part (C) TCM3 contains rubber heatersHS1 and HS2 attached to the surfaces of the concave part 5 a-1 and theconvex part 5 b-1 facing each other, and a temperature monitor HS′provided in the vicinity thereof. The rubber heater may be attached toone of the facing surfaces of the concave part 5 a-1 and the convex part5 b-1. A thermal conductor sheet may be attached instead of the rubberheater, or in alternative, both of them may be accumulated and attached.

[0066] The temperature difference of the isolation medium among thecapillaries of the multi-capillary array directed from the thermostatoven 5 to the detector part 1 can be suppressed by the temperaturecontrolling part (C) TCM3.

[0067] The fourth and temperature controlling part (E) TCM4 and TCM5will be described with reference to FIGS. 7A and 7B.

[0068] An upper gel block 34 is, for example, a block formed with anacrylic resin. A syringe 31, a gel storage container 25 and a buffercontainer (B) 15 are connected to the upper gel block 34. First to flowpath (E)s 31 a to 31 e are formed in the upper gel block 34.

[0069] A fresh gel 34 c is filled in the gel storage container 25. Thegel storage container 25 is connected to an end of the flow path (B) 31b through a tube path (A) 34 b. A first valve (check valve) V1 isprovided between an end of the tube path (A) 34 b and the flow path (B)31 b to allow only the flow of the gel from the gel storage container 25toward the upper gel block 34.

[0070] The syringe 31 and the upper gel block 34 are connected at aconnecting part 31′. When a pin valve PV is closed, and a plunger of thesyringe 31 is withdrawn for reducing pressure, the fresh gel 34 c in thegel storage container 25 is filled in the syringe 31 through the tubepath (A) 34 b, the flow path (B) 31 b and the flow path (A) 31 a. Whenthe pin valve PV is closed, and the plunger of the syringe 31 ispressed, the gel filled in the syringe 31 can be injected into thecapillaries 3 a through the flow path (A) 31 a, the flow path (C) 31 cand the flow path (D) 31 d. The gel functions as the isolation medium 4b inside the capillaries 3 a. The isolation medium 4 b after analysiscan be discharged outside the capillaries 3 a through the sampleinjecting end 3 b of the capillaries by again charging the fresh gel bythe foregoing operation.

[0071] A tube path (B) 15 b is provided between the flow path (E) 31 ein the upper gel block 34 and a flow path (F) 15 e of a lower gel block15 c to connect them. The lower gel block 15 c has a protrusion part 15c′ protruding downward. The pin valve PV for opening and shutting an endopening 15 d of the flow path (F) 15 e is attached to the lower gelblock 15 c. A tip end of the pin valve PV reaches the interior of theprotrusion part 15 c′. The isolation medium 4 b is filled in the flowpath (E) 31 e in the upper gel block 34, the tube path (B) 15 b, and theflow path (F) 15 e in the lower gel block 15 c. A buffer solution (B) 15a is filled in a buffer container (B) 15. The isolation medium 4 b maybe filled in the buffer container (B) 15 instead of the buffer solution.The isolation medium 4 b and the buffer solution (B) 15 a are in contactwith each other at the end opening 15 d of the flow path (F) 15 e.

[0072] Upon carrying out electrophoresis, the pin valve PV is moved inthe withdrawing direction (upward in the figure). A tip end 6 b′ of aelectrode (B) 6 b is grounded. Upon opening the pin valve PV, anelectrification path between the electrode (A) 6 a and the electrode (B)6 b through the buffer solution 11 a between the electrode (A) 6 a andthe sample injecting end 3 b of the capillaries, the isolation medium 4b filled in the sample injecting end 3 b of the capillaries, thecapillaries 3 a, the end part 3 d of the capillaries, the flow path (E)31 e in the upper gel block 34, the tube path (B) 15 b and the flow path(F) 15 e in the lower gel block 15 c, and the buffer solution (B) 15 abetween the end opening 15 d of the flow path (F) 15 e and the electrode(B) 6 b.

[0073] Therefore, when the pin valve PV is opened, and a voltage isapplied between the electrode (A) 6 a and the electrode (B) 6 b with thedirect current power supply 21 (FIG. 1), such a voltage can be appliedbetween both the ends of the electrification path (to be precise, thevoltage is applied to the buffer solutions positioned on both ends ofthe isolation medium, which are filled in the electrification path).Consequently, an electric current can be ran in the isolation medium 4 bfilled in the capillaries 3 a.

[0074] Upon opening the valve, the isolation medium 4 b is filled to theelectrode of the apparatus through a hole 15 b′ and a hole 15 b″.Therefore, an electric current can be ran in the isolation medium 4 bfilled in the capillaries 3 a.

[0075] In the case where the gel is filled in the capillaries 3 a, thepin valve PV is pressed. The electrification path formed with theisolation medium between the capillaries 3 a and the electrode on theapparatus is cut off with the pin valve PV. At this time, the isolationmedium can be injected from the gel storage container 25 to thecapillaries 3 a with the syringe 31.

[0076] As the temperature controlling part (D) TCM4, a rubber heater 36arranged on an outer surface of the tube path (B) 15 b and a temperaturemonitor 36 b attached to the outer surface of the tube path (B) 15 bexposed from an opening formed on the rubber heater 36. In alternative,it is possible to provide a rubber heater HT attached to an outersurface of the buffer container (B) 15 and a temperature monitor HT′attached to an exposed surface of the buffer container (B) 15 exposedfrom an opening formed on the rubber heater HT. Both of them may beprovided. A heater may also be provided on an outer surface of the uppergel block 34 or in the interior thereof.

[0077] The buffer solution (A) 11 a and the buffer solution (B) 15 a areprepared with, for example, TBE (a mixed solution oftris(hydroxymethyl)aminomethane, boric acid and EDTA(ethylenediaminetetraacetic acid)) or TAPS(N-tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid). The tube path(B) is similarly immersed in the buffer solution 15 a.

[0078] The buffer solutions 11 a and 15 a are filled in the buffercontainers 11 and 15, respectively. The electrode (A) 6 a and theelectrode (B) 6 b are immersed in the buffer solution 11 a and thebuffer solution 15 a, respectively. The buffer solutions 11 a and 15 aconnect electrically between electrodes and the separation medium in thecapillary.

[0079] In FIGS. 7A and 7B, an upper surface of the buffer solution (B)15 a is positioned above the end opening 15 d of the flow path (F) 15 e.Therefore, at least a part of the protrusion part 15 c′ of the lower gelblock 15 c is immersed in the buffer solution (B) 15 a.

[0080] The temperature difference of the isolation medium in thecapillaries of the multi-capillary array in the vicinity of the buffercontainer (B) can be suppressed by the temperature controlling part (D)TCM4.

[0081] The temperature controlling part (E) TCM5 will be described withreference to FIG. 1. The temperature controlling part (E) TCM5 controlsthe temperature of at least one of the upper gel block 34, the buffersolution (B) 15 a and the tube path (B) 15 b. It is preferred that thetemperature controlling part (E) TCM5 is constituted with a thermostatoven RH and a temperature monitor RH′ equipped therein.

[0082] The temperature difference of the isolation medium in thecapillaries of the multi-capillary array in at least one region of theupper gel block 34, the buffer solution (B) 15 a and the tube path (B)15 b can be suppressed by the temperature controlling part (E) TCM5.

[0083] A temperature controlling function provided in theelectrophoresis apparatus A will be described with reference to FIG. 8.

[0084] A temperature controlling part 26 is provided for carrying outthe entire temperature control, for example, PID control. Thetemperature controlling part 26 carries out the entire temperaturecontrol of the capillary electrophoresis apparatus A.

[0085] As described in the foregoing, a temperature monitor 31 isprovided in the thermostat oven 5 for monitoring the temperature insidethe thermostat oven 5. The temperature monitor 31 sends a signal S1 tothe controlling part 26, and the controlling part 26 sends a controlsignal S2 controlling the temperature in the thermostat oven 5 based onthe signal S1, whereby the basic temperature controlling part TCM0 isconstituted.

[0086] The temperature controlling part (A) TCM1 contains the rubberheater 12 b and the temperature monitor 12 d. The temperature monitor 12d sends a signal S3 to the controlling part 26, and the controlling part26 sends a control signal S4 controlling the temperature of the buffersolution (A) 11 a based on the signal S3 through the rubber heater 12 b.

[0087] The temperature controlling part (B) TCM2 contains the rubberheaters 8 a-1 and 8 a-2, the rubber heaters 8 b-1 and 8 b-2, and thetemperature monitor 8 c. The temperature monitor 8 c sends a signal S5to the controlling part 26, and the controlling part 26 sends a controlsignal S6 controlling the temperature of the isolation medium 4 b in thevicinity of the detector part 1 (in the detecting part 3 c of thecapillaries) based on the signal S5.

[0088] The temperature controlling part (C) TCM3 contains the rubberheaters HS1 and HS2 and the temperature monitor HS′. The temperaturemonitor HS′ sends a signal S7 to the controlling part 26, and thecontrolling part 26 sends a control signal S8 controlling thetemperature in the vicinity of the outlet of the 1 oven 5 based on thesignal S7 through the rubber heaters HS1 and HS2.

[0089] The temperature controlling part (D) TCM4 contains the heater 36and the temperature monitor 36 b, and further contains the heater HT andthe temperature monitor HT′, which are in contact with the outerperipheral surface of the buffer container (B) 15. The temperaturemonitor 36 b and the temperature monitor HT′ send a signal S9 to thecontrolling part 26, and the controlling part 26 sends a control signalS10 controlling the temperature of the isolation medium 4 b in thevicinity of the upper gel block 34 based on the signal S9 through theheaters 36 and HT.

[0090] The temperature controlling part (E) TCM5 contains the thermostatoven RH and the temperature monitor RH′ provided inside the thermostatoven RH. The temperature monitor RH′ sends a signal S11 to thecontrolling part 26, and the controlling part 26 sends a control signalS12 controlling the temperature of the thermostat oven RH based on thesignal S11.

[0091] While the rubber heater 12 b is provided in contact with thebottom surface of the buffer container (A) 11, it may be provided on theouter side surface of the buffer container (A) 11. The rubber heater 12b may be provided on one of the bottom surface and the side surface, andalso may be provided both of them. Furthermore, the buffer container (A)11 may be placed on a heater to carry out the temperature control.

[0092] The temperature controlling part 26 sends the temperature controlsignals S2, S4, S6, S8, S10 and S12 to the thermostat oven or theheaters based on the signals S1, S3, S5, S7, S9 and S11 sent from thetemperature monitors to the controlling part 26, whereby the temperaturecontrol is accomplished. As the temperature monitor, for example, aplatinum resistance thermometer and a thermocouple can be used.

[0093] As a method for temperature control, for example, the PID(proportional integral derivation) control may be used as described inthe foregoing. That is, such a method can be used that the detectionoutput from the temperature monitor is subjected to feedback to theheater and a Peltier element.

[0094] The temperature control is carried out to reduce the differenceof the temperatures in the radial direction of the plural capillaries 3a (i.e., the temperatures of the isolation medium in the capillaries atthe positions that are distant from the ends thereof by the samedistance). For example, when the temperature measured by the temperaturemonitor 31 attached to the thermostat oven 5 and the temperatures of theother parts are controlled to reduce the difference therefrom, there issuch a tendency that the temperature difference in the radial directionis reduced.

[0095] A method for using the multi-capillary electrophoresis apparatusA (i.e., a method for analyzing a sample) will be briefly describedbelow.

[0096] The isolation medium 4 b is filled in the capillaries 3 a byusing the syringe 31. For example, 16 capillaries 3 a are used.Subsequently, a sample 4 a containing plural kinds of DNA moleculeshaving different base lengths (DNA fragment sample) is introduced to theisolation medium 4 b filled in the capillaries 3 a through the side ofthe sample injecting end 3 b. The sample injecting end 3 b is immersedin the buffer solution (A) 1 a filled in the buffer container (A) 11.The PID control is carried out with the temperature controlling part 26to reduce the temperature difference among the plural capillaries 3 a.

[0097] The temperature control is carried out to reduce the temperaturedifference in the radial direction of the plural capillaries 3 a byusing at least one of the temperature controlling parts (A) to (E).Under the continued temperature control, a high voltage, for example,about from 10 to 20 kV, is applied between the electrode (A) 6 a(cathode) and the electrode (B) 6 b (anode) with the direct currentpower supply 21.

[0098] The DNA molecules migrate toward the electrode (B) 6 b(electrophoresed) because they are negatively filled. Differences inelectrophoresis migration velocity of the DNA molecules occurcorresponding to the base lengths thereof. The molecules having smallerbase lengths exhibit larger electrophoresis migration velocities torequire shorter periods of time to reach the detecting part 3 c. Uponirradiating the sample (DNA molecules) reaching the detecting part 3 cwith laser light L, identification markers attached to the DNA moleculesare excited to cause fluorescence. The fluorescence is subjected tophotoelectric transfer with a photo acceptance unit (CCD image sensor)provided in a CCD camera 71. The DNA molecules can be distinguished byelectric signals obtained from the CCD camera 71, and thus the speciesof DNA can be distinguished. Consequently, a sample containing DNAfragments is subjected to electrophoresis, and fluorescence from thesample is detected in the course of electrophoresis, whereby the DNAbase sequencing can be carried out for determining the base sequence.

[0099] The isolation medium 4 b and the sample 4 a can be discharged tothe outside through the path 31 e as described in the foregoing. It ispreferred that the isolation medium 4 b is replaced per analysis of onesample, and a fresh isolation medium 4 b is used for analysis of a newsample.

[0100]FIG. 9 shows standard deviations of electrophoresis time in thecase where 16 capillaries 3 a are used, in which a sample is injected,and the capillaries are simultaneously subjected to electrophoresisunder the same conditions. The data shown in FIG. 9 are experimentalresults in the case where the temperature controlling part (A) TCM1 andthe temperature controlling part (B) TCM2 are attached to the buffercontainer (A) 11 and the detector part 1, respectively.

[0101] In the case where no temperature controlling part is provided onthe buffer container (A) 11 and the detector part 1 (i.e., an ordinaryelectrophoresis apparatus), the standard deviation of electrophoresistime among the 16 capillaries 3 a is about 0.62. On the other hand, inthe case where only the temperature controlling part (A) TCM1 isprovided, the standard deviation of electrophoresis time of the 16capillaries 3 a is about 0.16. In the case where only the temperaturecontrolling part (B) TCM2 is provided, the standard deviation ofelectrophoresis time of the 16 capillaries 3 a is about 0.13. In thecase where both the temperature controlling part (A) TCM1 and thetemperature controlling part (B) TCM2 are provided, the standarddeviation of electrophoresis time of the 16 capillaries 3 a is about0.13.

[0102] It can be understood from the results that the difference of theelectrophoresis time among the 16 capillaries can be reduced byproviding the temperature controlling part on one of the buffercontainer (A) 11 and the detector part 1 for carrying out temperaturecontrol.

[0103] A multi-capillary electrophoresis apparatus according to amodified embodiment of the invention will be described with reference toFIG. 10. FIG. 10 is a cross sectional view showing the structure of thedetector part 1 of the multi-capillary electrophoresis apparatus.

[0104] As shown in FIG. 10, in the detector part 1 of themulti-capillary electrophoresis apparatus according to the modifiedembodiment, a pressing plate 78 and a good thermal conductor 7 d, suchas Al, covering at least a part of the outer side surface of thepressing plate 78 are provided on the side opposite to a capillarysupporting part 77 with the capillaries 3 a being inserted therebetween.A Peltier element 81 is attached in contact with the outer peripheralsurface of the good thermal conductor 7 d. The other constitutions thanthose noted herein are the same as in the multi-capillaryelectrophoresis apparatus described in the foregoing.

[0105] The Peltier element 81 is connected to a direct current powersupply 91. More specifically, the Peltier element 81 has an n-typesemiconductor layer 81 a, a p-type semiconductor layer 81 b, anelectrode 81 d that is formed on one surface of the n-type semiconductorlayer 81 a and is connected to a negative electrode of a variable directcurrent power supply 91 capable of changing the output voltage, anelectrode 81 c that is formed on one surface of the p-type semiconductorlayer 81 b and is connected to a positive electrode of the variabledirect current power supply 91, and a common electrode 81 e that isformed on the surfaces of the n-type semiconductor layer 81 a and thep-type semiconductor layer 81 b opposite to the one surfaces thereof andis commonly connected to both the semiconductor layers 81 a and 81 b.

[0106] A good thermal conductor 75 is formed in contact with a CCD imagesensor 73. The CCD image sensor 73 and the common electrode 81 e carryout mutual heat exchange through the good thermal conductor 75. Atemperature monitor is provided on the good thermal conductor 75. Anelectric signal based on the temperature measured by the temperaturemonitor is sent to the controlling part 26 (FIG. 1). The controllingpart 26 sends a control signal for determining the voltage to be appliedbased on the electric signal to the variable direct current power supply91.

[0107] In the case where the temperature measured by the temperaturemonitor 8 a′ is too low, for example, the controlling part 26 sends sucha signal to the variable direct current power supply 91 that the voltageapplied to the Peltier element 81 is increased. Upon increasing thevoltage applied to the Peltier element 81, the temperature on the sideof the electrode 81 c and the electrode 81 d is increased, andtherefore, the temperature of the capillaries 3 a is increased. On theother hand, the temperature of the electrode 81 e is decreased, and thusthe CCD solid image pickup element 73 can be cooled through the goodthermal conductor 75. Accordingly, the noise of the CCD solid imagepickup element 73 can be reduced.

[0108] The invention has been described with reference to the specificembodiments, but the invention is not construed as being limitedthereto. It is apparent to a skilled person in the art that othervarious changes, improvements and combinations can be applied to theinvention without deviating from the spirit thereof.

[0109] According to the multi-capillary electrophoresis apparatus of theinvention, fluctuation of the electrophoresis migration velocity in theradial direction of plural capillaries can be suppressed.

[0110] Therefore, analysis of a sample can be carried out in a moreaccurate manner by using the multi-capillary electrophoresis apparatus.

What is claimed is:
 1. A multi-capillary electrophoresis apparatuscomprising: a multi-capillary array having an isolation medium filledtherein for isolating a sample, a sample injecting end on one endthereof, and a detector part for acquiring information depending on thesample at a position remote from the sample injecting end; a voltageapplying part for applying a voltage to an electrification pathcomprising the sample injecting end and the detector part; a thermostatoven containing all or a part of the multi-capillary array except forthe sample injecting end; a buffer container containing a buffersolution, in which the sample injecting end is immersed; and atemperature controlling part for controlling a temperature of the buffersolution.
 2. A multi-capillary electrophoresis apparatus as claimed inclaim 1, wherein the temperature controlling part comprises a heater incontact with the buffer container.
 3. A multi-capillary electrophoresisapparatus comprising: a multi-capillary array having an isolation mediumfilled therein for isolating a sample, a sample injecting end on one endthereof, and a detector part for acquiring information depending on thesample at a position remote from the sample injecting end; a voltageapplying part for applying a voltage to an electrification pathcomprising the sample injecting end and the detector part; a thermostatoven containing all or a part of the multi-capillary array except forthe detector part; and a temperature controlling part for controlling atemperature of the detector part.
 4. A multi-capillary electrophoresisapparatus as claimed in claim 3, wherein the temperature controllingpart comprises a heater arranged in a vicinity of the detector part. 5.A multi-capillary electrophoresis apparatus comprising: amulti-capillary array having an isolation medium filled therein forisolating a sample, a sample injecting end on one end thereof, and adetector part for acquiring information depending on the sample at aposition remote from the sample injecting end; a voltage applying partfor applying a voltage to an electrification path comprising the sampleinjecting end and the detector part; a thermostat oven containing all ora part of the multi-capillary array except for the sample injecting endand the detector part; a buffer container containing a buffer solution,in which the sample injecting end is immersed; a first temperaturecontrolling part for controlling a temperature of the buffer solution;and a second temperature controlling part for controlling a temperatureof the detector part.
 6. A multi-capillary electrophoresis apparatus asclaimed in claim 5, wherein the first temperature controlling partcomprises a first heater for heating the buffer solution and a firstsensor for measuring a temperature of the buffer solution; and thesecond temperature controlling part comprises a heater for heating thedetector part and a second sensor for measuring a temperature of thedetector part.
 7. A multi-capillary electrophoresis apparatuscomprising: a multi-capillary array having an isolation medium filledtherein for isolating a sample, a sample injecting end on one endthereof, and a detector part for acquiring information depending on thesample at a position remote from the sample injecting end; a voltageapplying part for applying a voltage to an electrification pathcomprising the sample injecting end and the detector part; a thermostatoven containing all or a part of the multi-capillary array except forthe detector part; and a temperature controlling part for controlling atemperature in a vicinity of an outlet of the thermostat oven on a sideof the detector part.
 8. A multi-capillary electrophoresis apparatuscomprising: a multi-capillary array having an isolation medium filledtherein for isolating a sample, a sample injecting end on one endthereof, and a detector part for acquiring information depending on thesample at a position remote from the sample injecting end; a voltageapplying part for applying a voltage to an electrification pathcomprising the sample injecting end and the detector part; a thermostatoven containing all or a part of the multi-capillary array; a gel blockarranged outside the thermostat oven and charging the isolation mediumin the capillary array; and a temperature controlling part forcontrolling a temperature of the gel block.
 9. A multi-capillaryelectrophoresis apparatus comprising: a multi-capillary array having anisolation medium filled therein for isolating a sample, a sampleinjecting end on one end thereof, and a detector part for acquiringinformation depending on the sample at a position remote from the sampleinjecting end; a voltage applying part for applying a voltage to anelectrification path comprising the sample injecting end and thedetector part; a thermostat oven containing all or a part of themulti-capillary array; a flow path connected to the multi-capillaryarray and having the isolation medium filled therein; and a temperaturecontrolling part for controlling a temperature of the flow path.
 10. Amulti-capillary electrophoresis apparatus comprising: a multi-capillaryarray having an isolation medium filled therein for isolating a sample,a sample injecting end on one end thereof, and a detector part foracquiring information depending on the sample at a position remote fromthe sample injecting end; a voltage applying part for applying a voltageto an electrification path comprising the sample injecting end and thedetector part; a thermostat oven containing all or a part of themulti-capillary array; a flow path connected to the multi-capillaryarray and having the isolation medium filled therein; a buffer containercontaining a buffer solution, in which the flow path is immersed; and atemperature controlling part for controlling a temperature of the buffersolution.
 11. A multi-capillary electrophoresis apparatus as claimed inclaim 10, wherein the temperature controlling part comprises a heater incontact with the buffer container.
 12. A multi-capillary electrophoresisapparatus as claimed in claim 1, wherein the detector part comprises aphoto accepting unit receiving excitation light generated uponirradiating the sample with laser light, and a Peltier element coolingthe photo acceptance unit or heating the detector part.